1957 Custom Triumph Thunderbird

atom1atom2atom3atom4atom5You may not know that the the 50’s production 650cc Thunderbird (6T) was a low-compression tourer, created by Triumph to satisfy the American demand for motorcycles suited to long distance riding… But I am sure you know that the Triumph brand received considerable publicity in the United States when Marlon Brando rode a 1950 Thunderbird 6T in the 1953 motion picture “The Wild One.” It’s a Triumph from this era that Atom Bomb Custom Motorcycles helped to rebuild and customize for Corey Theuerkauf whose father passed away before he had a chance to complete the project with original parts he had chased and accumulated during the last 20 years.

atom6atom7atom8Atom Bomb Custom Motorcycles specializes in destroyed and neglected Triumphs and BSAs bikes, bringing them back to life with as many as possible original parts. But it’s not always possible, like in this case where an aftermarket hardtail for a unit Triumph had been incorrectly welded on, making the frame crooked and unfit for safe riding. Keeping the factory neck, the shop had to built a complete custom frame and modified an original Wassell tank to fit on it. Rear fender is born from a 1936 Ford spare tire ring that shop owner Clay Rathburn got from his father years ago. A set of shaved and polished late model forks were installed on the front along with an old spool that the shop kept for the right project.

Of course, engine & tranny were re-built following Triumph factory original specifications. Vertical oil tank, handlebars, custom exhaust and many bits are in-house fabricated. End result is a very clean tribute Triumph bobber/chopper to remember Corey’s dad. Atom Bomb Custom Motorcycles.


29 Responses to “1957 Custom Triumph Thunderbird”

  1. 1 Sharkey Jun 5th, 2014 at 8:35 am

    Some super clean bobbers on their site…sadly, saw no BSA’s…

  2. 2 A1 MIKE Jun 5th, 2014 at 8:48 am

    clay is a talented dude! and this triumph is spot on!

  3. 3 skinny denny Jun 5th, 2014 at 9:01 am

    Very nice. My brother had a 1963 TR6 before his Harleys. Probably about a 50 mile range with that tank. Probably doesn’t weigh over 300 pounds. Sweet.

  4. 4 Roger Davenport Jun 5th, 2014 at 9:01 am


  5. 5 Kirk Perry Jun 5th, 2014 at 9:55 am

    A ’51 Thunderbird was my first twin. Bought it in the rain. No front fender. Couldn’t believe how much pull there was between 3rd and 4th. My previous ride that I just stepped off of was a 10 hp. , competition Tiger Cub, so the t-bird was more than thrilling.
    In 1961Texas, the original title was signed-off on the back. A new signature every two years on average. There was room for a list of about 10 owners. My 40 cu. in. T-bird was first painted bronze and owned by Glen Baines, He threw a 110 customer paper route, stuffing 55 rolled weekday papers in a dual canvas saddlebag thrown over the back fender that read “Houston Chronicle” on the sides.

    A guy at the paper-stand kept bugging Glen for a ride, so one afternoon Glen caved and said “OK, hop on!”
    As soon as the fellow had positioned him shelf on the Bates cheese-block pillion seat, Glen took off and rapidly increased the speed as the passenger’s legs began to rise over his head.
    It wasn’t until Glen wound the bike out in 3rd and shifted to 4th, that the inertia was too much to overcome and the fellow rolled off the back and into the street.
    I bought the bike from Dick Venables, who owned a (laughing) Bear Brake shop for $125. because his wife needed a washing machine.

  6. 6 Kirk Perry Jun 5th, 2014 at 10:00 am

    There is rear suspension. The back axle floats inside the drum – suspended in the center by a jillion opposing springs.

  7. 7 Kirk Perry Jun 5th, 2014 at 10:27 am

    Actually, the T-bird was only 28 cu. in., whereas most 650cc twins were 30 cu. in.

  8. 8 P. Danbury Jun 5th, 2014 at 10:32 am

    Love it.

  9. 9 skinny denny Jun 5th, 2014 at 10:54 am

    @Kirk Perry
    A 650 is actually a 40 c.I. A 750 is 45 c.I. An 883 is 53.9 rounded off to 55. A 1000 is a 61. A 500 is actually, I believe, 30.5 c.i. This is all from memory, so you might want to Google it to be sure. I’m a trivia nut!

  10. 10 Kirk Perry Jun 5th, 2014 at 11:15 am

    And a smooth shifting Burman transmission. Boy those were nice.

  11. 11 Rodent Jun 5th, 2014 at 1:31 pm

    Looks like it’s out of oil, no spots underneath! Great looking ride! God save Joseph Lucas, NOT!

  12. 12 James just another Crazy Kiwi Jun 5th, 2014 at 2:21 pm

    I owned a 51 Thundrebird for 15 years sold it to get the cash together to buy a new Road King in 94.
    Something I still regret.
    She had a Mk3 Sprung Hub, high out put racing mag and racing Conrods that were polished and notched. They were made in the States. I cannot remember the brand
    She was low compression and ran beautifully.
    I have tried to get her back………sigh.
    The Rigid sprung hub Thunderbirds were one of Turners greatest designs. Aesthetically just a beautiful motorcycle.
    Americans apparently did not go so much for the Shell Blue and a number were painted black and called Black Birds. Or so the legend goes.
    I think the Thunderbird in the Wild One was Brando’s personal ride.
    I wonder what happened to it ?

    And that Motorcycle above is a very nice custom Triumph.

  13. 13 Kirk Perry Jun 5th, 2014 at 2:31 pm

    “A 650 is actually a 40 c.I. A 750 is 45 c.I. An 883 is 53.9 rounded off to 55. A 1000 is a 61. A 500 is actually, I believe, 30.5 c.i. This is all from memory”
    Not bad. How old are you …35?
    Everytime I’ve hit the “submit” button, I’ve regretted it about 5-seconds later. Furry synapse. 🙂

    These numbers used to just roll-off the top for me…. one of them was “34 cubic, 650 BSA”

    Guess I’ve been wrong all these years – now struggling to deal with it.

  14. 14 skinny denny Jun 5th, 2014 at 2:47 pm

    @Kirk Perry
    I’m actually 60. My memory is better than ever, unfortunately my body isn’t! Love those old Brit bikes. Wish I was in a “Sonoma Coma” right about now! Have a good one!

  15. 15 Kirk Perry Jun 5th, 2014 at 2:58 pm

    That 1959 Triumph Cub scrambler I mentioned? I bought that “used” from W&W Triumph out on the Gulf Freeway, southeast of Houston. A red and birch-white job – with a worn rear sprocket, that after awhile would allow the chain to skip teeth and not move forward at all. I don’t even think it was 10 h.p.
    My bother was working for Pridgen H-D (actually just hanging around the shop) and was reduced to riding a 2-cycle Topper in the dead of winter, from Spring Branch over to freakin’ Pasadena. A long trip. Round-trip.
    The Topper got sold to a customer, so he started using my scrambler and wound the snot out of it – trying to keep up with freeway traffic getting over to Pridgen’s.
    Long story short, a group of Texite bikers all piled-out here for the Del Mar Nationals in early 2000.
    Jimmy Whitlock, one of the “W’s” in W&W was with them. As soon as we were introduced, I blurted-out, “I bought my Triumph Cub from you back in 19………”
    Before I could finished, he replied, “I’m sorry but your warranty has expired.”

  16. 16 Corey Theuerkauf Jun 5th, 2014 at 3:42 pm

    This bike is more than I had ever imagined, each ride gets better and better. Clay took an emotional build, with a client needing advice and direction, he owned it! He was a pleasure working with and was always there via phone or email to keep me up-to date through the rough times and the exciting times filled with anticipation. Class act and even better craftsman! Glad to see you getting some pub for a job well done.

    Old Man always said…”Always in the Wind!” I agree its the only place to be!!!

  17. 17 Kirk Perry Jun 5th, 2014 at 4:07 pm

    I have photos of my T-bird that look so much like this nice ’57. Mine has the same little bates? headlamp. The same rubber fork boots, chopped rear fender, but the brit one that shipped with it. It has that ridge running down the middle. Made them strong. Would hold the weight of newspapers. A lot of these T-birds wound-up getting the faring stuff stripped and looking just like this. These pipes are nice. I have a picture of mine. Just like these stacked shotguns, except the pipes were up-swept with bates? bell megaphones. One pipe on each side. Triumph aftermarket, even in 1959. The photo I took from behind shows one megaphone aout 1/2″ higher than the other. It also had the obligatory cast aluminum tail lamp.
    Bates made a bunch of hi-quality custom stuff that was really good. The leather fender wedge pillion, nice 2-piece megaphones, tips were removable.
    One thing that has stumped me the day someone reminded me the reason, which I forgot, is that my T-bird ran without a battery. No way could I have afforded a battery, much less a charger in 1962. I don’t know if the lights worked. Probably not, but you could get by with no lights in the semi-rural surroundings where we lived. No big deal unless you hit a car backing out of a driveway, which Blake did to his BSA 500, Shooting Star. Pow! 🙂

  18. 18 nicker Jun 5th, 2014 at 6:08 pm

    Brings back some very fond memories….. 🙂

    – Those engine cases are from a late model pre-unit alternator bike.
    – While the trans mission is from an earlier pre-unit generator bike.

    The transmission is, however a Triumph transmission (not a Burman box).
    Triumph made their transmission in Wide Ratio, Standard Ratio, and Close Ratio gearing options.

    Regarding “high out put racing mag”…. ?????
    Spark came from either a Model-18 D2 distributor, a Lucus mag, or a BTH mag.

    The factory race kit (part #CP100, alternatively #CP101) list a lot of stuff , but no “racing mag”….
    Keeping with the later model engine cases (and no spark advance lever) it would appear the mag has an auto advance mechanism.

    This scooter has no “Sprung Hub” suspension.

    Just some trivia.

  19. 19 Kirk Perry Jun 5th, 2014 at 6:54 pm

    “Keeping with the later model engine cases (and no spark advance lever) it would appear the mag has an auto advance mechanism. ”
    It did. There was no manual spark advance on mine. Centrifugally weighted like a Shovel’s maybe. A two-piece crankshaft I was told.
    There was a factory, aluminum cylin-box behind the top of the crankcase. It had a knurled cap-end with at least one wire exiting a terminal post. I never touched anything. Just rode it. And for sure my headlight was just there to keep police from pulling it over. I never remember a switch – toggle or otherwise. Definitely no brake switch.
    People in Texas would only get so far with a build. If they ran into a jam, but it would run, they’d just ride it.

  20. 20 Mack Jun 5th, 2014 at 8:22 pm

    Long live Kirk perry

  21. 21 Kirk Perry Jun 5th, 2014 at 9:38 pm

    We’re the last of the Mohicans that rode actually rode them.
    Imagine what life was like before the internet. Snails-pace into oblivion, instead of fast-pace.

  22. 22 James just another Crazy Kiwi Jun 6th, 2014 at 1:02 am

    It was a Lucas Mag ( Lucas the Prince of Darkness)
    But supposedly a racing version… ? hopefully I was not ripped off it is too long ago to track down the culprit.
    The Mk3 sprung hub was the way to go apparently the earlier ones tended to seize.
    They looked good and would be ok on the above Sickle
    I am thinking about what to do next and I have to admit for allot of passion for Pre Unit Triumphs.
    They are cool looking, fun and easy to ride.

    Crashed mine once, rode off a bank and hit a tree in mid air. Had the side car on with my mates girlfriend in it. The top of the chair left with her and she slid down the paddock on her arse.
    She had inner and out skid marks…..heh heh

  23. 23 Sportster Mike Jun 6th, 2014 at 2:26 am

    Simply is as simply does…
    And I didn’t think it was a sprung hub, as its too narrow – don’t they go all the way through the hub?

  24. 24 skinny denny Jun 6th, 2014 at 9:23 am

    If Indian Larry would have ever built a Trumpet, it would probably have looked something like this. I love the “keyboard wars” on this site! One of my cousins had a 1965 or 1966 Bonneville T.T. Special . I was only about 12 or 13 at the time so I rode on the back behind Jim. That was one cool Brit bike!

  25. 25 Boomer Jun 6th, 2014 at 10:25 am

    Nicely done and clean. The opposite shift/foot brake reminds me of a ’68 Sporty I built from the ground up. My first ground up build actually. Thing is after a year of finding parts and getting it together I found I just couldn’t get used to the right hand shifter and would hit it like a brake without thinking. I sold it before I trashed the trans. Great fun and experience though with no regrets.

    Good to see the old Trumpets still being done up once in a while. Beezers too. They are almost like the Vincents in sheer mechanical beauty methinks.

  26. 26 nicker Jun 7th, 2014 at 9:09 pm


    “…A two-piece crankshaft I was told…”

    That set of cases (scooter in the pic) should-a come with a one piece crank……. with the dreaded “sludge trap.”

    Big-D told T.T. motors (Berkeley CA) the late model cranks were good to 70 HP.
    After that ya needed a Sonny Rout forged, trap-less, unit.

    My dream, a 70+ HP Triumph………. 🙂


  27. 27 nicker Jun 7th, 2014 at 9:17 pm

    The big sprung hubs were heavy and really didn’t inspire handling confidence.

    And in a day and age where you didn’t get much in the way of “Consumer warnings,” the service manual had an explicit WARNING to “Not disassemble” the spring enclosure.

    I have only one and doubt i’ll ever use it.


  28. 28 James just another Crazy Kiwi Jun 7th, 2014 at 9:49 pm

    Road mine for 15 years and the story goes the Mk1 Hub and 2 were not good, the 3 was very good. I cannot even remember how to tell the difference now.
    I have read that some where, I think classic bike did an article on them many years ago
    I cannot ride on gravel , just hopeless. Yet on the Thunder Bird I was a regular Jay Springsteen ( I Wish) The Sprung hub was great on gravel, the low centre of gravity and flexible motor all helped too.
    Wish she was still in the shed

  29. 29 Blackmax Jun 9th, 2014 at 4:38 pm

    It’s clean, its looks GREAT & from the comment of Corey Theuerkauf, it RUNS!!!
    As long as he enjoys it ,what else would anybody else have to say ??
    Nuff Said, again, one BAC (Bad Ass Cycle) !!!!

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